Skip to main content
USGS - science for a changing world
Advanced Search

Filters: Tags: Modeling (X)

499 results (19ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
thumbnail
We will develop a set of linked models to help predict the effects of climate change on rivers and endangered species. These will include watershed- and reach-scale models to predict streamflow, water temperatures, and other fish habitat metrics under various climatic scenarios for the reaches used by species listed under the Endangered Species Act (ESA), plus a combined bioenergetics and life-cycle model (to be done by the U.S. Geological Survey [USGS]) to assess the impact of these factors on fish growth, reproduction, and survival. We propose to test the model framework at a site on the Methow River, Washington, to explore additional opportunities for collaboration and model development.
thumbnail
Pogo Mine Project: An Introduction The Project: The proposed Pogo Gold Mine would be located about 38 miles northeast of Delta Junction, Alaska, near the Goodpaster River (see figure 1). Teck-Pogo, Inc., the "applicant," plans to develop the mine on state-owned land. It would be an underground mine with a surface mill producing up to 500,000 ounces of gold each year. The applicant hopes to begin construction in 2002, and proposes to operate the mine 24 hours a day, 365 days a year, for about 12 years. This predicted mine-life is based on existing information; on-going exploration could increase the life of the mine. The project would employ up to 385 employees. Workers would be housed on site. An airstrip would...
thumbnail
A comprehensive list of 38 categories of anthropogenic drivers of change in marine ecosystems developed through expert workshops (S1) was assessed for data availability on a global scale. We intentionally did not further subdivide these categories into unique drivers (e.g. each specific type of pollutant) as this would lead to over-emphasis of certain activities when impacts are summed. We limited our analyses to anthropogenic drivers with pre-existing global coverage or those for which we could assemble or develop global coverage. Although many regional-scale data and data with a global scope but incomplete coverage exist for a variety of specific human activities, inclusion of these data would bias global comparisons...
thumbnail
This dataset represents presence of white pine (Pinus strobus) at year 100 (2095) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Contemporary harvest rates and intensities were simulated.
To determine the dominant processes controlling nitrogen (N) dynamics in soils and increase insights into soil N cycling from nitrogen isotope (?15N) data, patterns of 15N enrichment in soil profiles were compiled from studies on tropical, temperate, and boreal systems. The maximum 15N enrichment between litter and deeper soil layers varied strongly with mycorrhizal fungal association, averaging 9.6 � 0.4? in ectomycorrhizal systems and 4.6 � 0.5? in arbuscular mycorrhizal systems. The 15N enrichment varied little with mean annual temperature, precipitation, or nitrification rates. One main factor controlling 15N in soil profiles, fractionation against 15N during N transfer by mycorrhizal fungi to host plants, leads...
thumbnail
Boreal regions contain more than half of the carbon in forested regions of the world and over 60% of the world's surface freshwater. Carbon storage and the flood control and water filtration provided by freshwaters and wetlands have recently been identified as the most important ecosystem services provided by boreal regions, with a value many times greater than current resource exploitation. Ecosystem services and sensitive ways of detecting their impairment have so far not been fully included in boreal conservation planning. Climate warming, via its effect on permafrost melting, insect damage, and forest fire, threatens to trigger large positive carbon feedbacks that may enhance the concentrations of greenhouse...
Snow covered area (SCA) observations from the Landsat Enhanced Thematic Mapper (ETM+) were used in combination with a distributed snowmelt model to estimate snow water equivalent (SWE) in the headwaters of the Rio Grande basin (3,419 km2) - a spatial scale that is an order of magnitude greater than previous reconstruction model applications. In this reconstruction approach, modeled snowmelt over each pixel is integrated over the time of ETM+ observed snow cover to estimate SWE. Considerable differences in the magnitude of SWE were simulated during the study. Basin-wide mean SWE was 2�6 times greater in April 2001 versus 2002. Despite these climatological differences, the model adequately recovered SWE at intensive...
A severe sustained drought in the Colorado River Basin would cause economic damages throughout the Basin. An integrated hydrologic-economic-institutional model introduced here shows that consumptive water users in headwaters states are particularly vulnerable to very large shortfalls and hence large damages because their rights are effectively junior to downstream users. Chronic shortfalls to consumptive users relying on diversions in excess of rights under the Colorado River Compact are also possible. Nonconsumptive water uses (for hydropower and recreation) are severely affected during the worst drought years as instream flows are reduced and reservoirs are depleted. Damages to these uses exceeds those to consumptive...
thumbnail
This dataset represents presence of Jack Pine (Pinus banksiana) in Minnesota (USA) at year 50 (2045) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Restoration harvest rates and intensities were simulated.
thumbnail
This dataset represents presence of Sugar Maple (Acer saccharum) in Minnesota (USA) at year 0 (2145) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Contemporary harvest rates and intensities were simulated.
thumbnail
Detailed observations of stream, soil, and groundwater chemistry were used to determine the role of fire, permafrost and snowmelt processes on the fluxes of carbon, nitrogen and major solutes from interior Alaskan catchments. We examined an experimentally burned watershed and two reference watersheds that differ in permafrost coverage (high, 53%; medium-burn, 18%; and low, 4%) during the FROSTFIRE prescribed burn in July 1999. The fire elevated stream nitrate concentrations for a short period during the first post-fire storm, but nitrate declined thereafter, suggesting that less severe fires that leave an intact riparian zone may have only a short-term effect on stream chemistry. Nevertheless, we found fundamental...
thumbnail
This dataset contains csv files in support of the conclusions published in "Water use demand in Mediterranean California under multiple scenarios of developed and agricultural land use " in the journal PLOS One. We used the USGS's LUCAS model to examine a broad suite of spatially explicit future land use scenarios and their associated county-level water use demand, including the historical (1992-2011) and projected periods (2012-2062) across 40 Monte Carlo simulations.We examined a range of potential water demand futures sampled from a 20-year record of historical (1992-2012) data to develop a suite of potential future land change scenarios from 2012-2062. These scenario simulations include a 1) business-as-usual...
thumbnail
The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering 1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past 4 million years and the configuration of permafrost to depths of 100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the...
thumbnail
This thesis is an investigation of the biophysical controls on the three modes of methane (CH4 ) release from a boreal peatland: diffusion, plant-mediated transport and ebullition. My objectives were to (1) quantify the total CH4 flux of a permafrost thaw-affected peatland, (2) establish the relative importance of the three modes of CH4 release in these systems, and (3) identify key biotic and abiotic controls on individual transport mechanisms. Results showed that ebullition and plant-mediated transport were the dominant pathways for CH4 release and that traditional approaches for measuring total CH4 flux from peatland soils underestimated total efflux by not capturing ebullition. Further, results from a laboratory...
thumbnail
This paper examines changes in climate with respect to permafrost and engineering design in Arctic regions. Current understanding of climate changes, predictive modeling, and climate data were studied. Inconsistencies and differences were noted, discussed, and evaluated using comparisons of the resulting climate data and graphs. A graphical analysis was done to compare different methods of data analysis and different visual interpretations of historical climate trends. The graphical analyses in this paper should be used as a guide for determining the accuracy of thermal design parameters applied to current project designs. The methodology used to evaluate raw data can greatly affect the output values used in design....
thumbnail
Permanent electrode arrays were set up at ten monitoring sites from Whitehorse, Yukon, to Fort St. John, British Columbia, in order to gain a clearer perspective of the effectiveness of electrical resistivity tomography (ERT) monitoring over an annual cycle of freezing and thawing. This research forms part of a longer-term project that is attempting to use ERT to examine changes in permafrost resulting from climate change. Inter-site and intra-site variability were examined by installing and maintaining data-loggers to monitor active layer and shallow permafrost temperatures, air temperatures, and snow depths at each site from August 2010-August 2011. Additional site information was collected on each ERT survey...


map background search result map search result map Evaluating Climate-Induced Runoff and Temperature Change on Stream Habitat Metrics for Endangered or Threatened Fish - BOR Project FY2011 Minnesota (USA) Climate Change Project: White Pine at Year 100 (2095), assuming emissions scenario B2, Hadley3 GCM, contemporary harvest rates and intensity Minnesota (USA) Climate Change Project: Jack Pine at Year 50 (2045), assuming emissions scenario B2, Hadley3 GCM, restoration harvest rates and intensity Minnesota (USA) Climate Change Project: Sugar Maple at Year 150 (2145), assuming emissions scenario B2, Hadley3 GCM, contemporary harvest rates and intensity Airborne electromagnetic imaging of discontinuous permafrost The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: implications for post-thaw carbon loss Physical and ecological controls on methane release from a boreal peatland in interior Alaska Exploring the sensitivity of soil carbon dynamics to climate change, fire disturbance and permafrost thaw in a black spruce ecosystem Seasonal cycling in electrical resistivities at ten thin permafrost sites, southern Yukon and northern British Columbia Geometry of oriented lakes in Old Crow Flats, northern Yukon Comprehensive conservation planning to protect biodiversity and ecosystem services in Canadian boreal regions under a warming climate and increasing exploitation Export of carbon, nitrogen and major solutes from a boreal forest watershed: The influence of fire and permafrost POGO Gold Mine EIS/NEPA Project Progress in space-borne studies of permafrost for climate science: Towards a multi-ECV approach Mediterranean California’s water use future based on scenarios of land use change 1992-2062 - Tabular Data POGO Gold Mine EIS/NEPA Project Evaluating Climate-Induced Runoff and Temperature Change on Stream Habitat Metrics for Endangered or Threatened Fish - BOR Project FY2011 Physical and ecological controls on methane release from a boreal peatland in interior Alaska Export of carbon, nitrogen and major solutes from a boreal forest watershed: The influence of fire and permafrost Exploring the sensitivity of soil carbon dynamics to climate change, fire disturbance and permafrost thaw in a black spruce ecosystem Geometry of oriented lakes in Old Crow Flats, northern Yukon Minnesota (USA) Climate Change Project: Sugar Maple at Year 150 (2145), assuming emissions scenario B2, Hadley3 GCM, contemporary harvest rates and intensity Minnesota (USA) Climate Change Project: White Pine at Year 100 (2095), assuming emissions scenario B2, Hadley3 GCM, contemporary harvest rates and intensity Minnesota (USA) Climate Change Project: Jack Pine at Year 50 (2045), assuming emissions scenario B2, Hadley3 GCM, restoration harvest rates and intensity Airborne electromagnetic imaging of discontinuous permafrost Seasonal cycling in electrical resistivities at ten thin permafrost sites, southern Yukon and northern British Columbia The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: implications for post-thaw carbon loss Mediterranean California’s water use future based on scenarios of land use change 1992-2062 - Tabular Data Progress in space-borne studies of permafrost for climate science: Towards a multi-ECV approach Comprehensive conservation planning to protect biodiversity and ecosystem services in Canadian boreal regions under a warming climate and increasing exploitation